Process of honing



Nov. 15, 1955 H. D. STUCK PROCESS OF HONING 2 Sheets-Sheet 1 Filed Aug. 8, 1951 INVENTOR.

HAROLD D. STUC'H HTTORNEYS Nov. 15, 1955 H. D. STUCK PROCESS OF HONING 2 Sheets-Sheet 2 Filed Aug. 8, 1951 INVENTOR.

HAROLD D STUCK Pia/1AM 73W ATTOR NEY5 United States Patent ()fifice 2,723,515 Patented Nov. 15, 1955 PROCESS or HONING Application August 8, 1951, Serial No. 240,824

' Claims; (Cl. 51-235) This invention relates to a new process of honing machine knives with a handoperable hone. My new process of honing is especially useful in sharpening the cutting edges of long knives used in the paper industry to cut or trim stacks of paper, paperboard, plastic or similar sheet materials.

Such knives are usually straight and may be three or more feet in length and several inches in height. They are formed with a bevel of predetermined angle which must be maintained keen and true for the best performance. For convenience I call the beveled face, the narrow cutting face, and I call the other cutting face, the wider cutting face, these two faces meeting to form a straight cutting edge. Both faces contain a predetermined concave measured in thousandths of an inch which must be maintained as nearly as possible after sharpening.

The principal object of my invention is to provide a process for producing a sharper and truer cutting edge on such knives in a shorter time than has been possible in the past, and at the same time to eliminate any feather on the cutting edge.

For many years, it has been customary in honing machine knives to first hone the entire beveled face, secondly to hone the cutting edge to break the feather edge thereon, thirdly to hone the entire wider cutting face and fourthly to again hone the beveled face. An object of my invention is to eliminate entirely the second step of honing the cutting edge to break the feather edge thereon which,'heretofore, has blunted the edge. I do so by substituting a new third step consisting of honing only the portion of the wider concave cutting face extending from the low point of the concavity to the cutting edge rather than honing the entire wider cutting face.

Still another object of my invention is to eliminate the necessity of repeatedly stopping the honing operation to relubricate the hone by providing a porous hone which absorbs liquid by capillary attraction'from its lower face to its upper face in one immersion. Since my hone is thus permeated throughout with my lubricating and wetting agent, wear on the hone continually uncovers a new lubricated, abrasive surface and an entire knife canbe honedafter one such immersion.

In the drawings:

Fig. l is a plan view of the preferred form of hone used in my process.

Fig. 2 is a side elevation, in section on line 2-2 f Fig. 1 of said hone.

Fig. 3 is a side elevation of the hone.

Fig. 4 is a side elevation in section showing a machine knife in position in blocks for the step of honing the narrow concave cutting face with coarse abrasive in my new process. a

Fig. 5 is a similar view showing the machine knife in position on the blocks for the step of honing a portion of the wider concave cutting face thereof with a line abrasive.

Fig. 6 is a plan view showing the path of the hone in the second step of my process.

Fig. 7 is a plan view showing the path of the hone in the first and third step of my process.

Fig. 8 is a view similar to Fig. 4 showing the machine knife returned to the position of Fig. 4 for the step ofhoning the narrow concave cutting edge with a fine abrasive.

Fig. 9 is a View similar to Fig. 4 showing the position of the knife during testing.

Fig. 10 is a side elevation, in section, showing the step of saturating my new porous Home with the lubrieating and wetting agent and Fig.11 is a plan view on line 11---11 of Fig. 10.

As shown, H is the preferred form of hand operable hone, used in my process, it being of cylindrical shape and provided with a peripheral finger groove 11. Hone H is annular, there being a circular opening 12 about one and one half inches in depth through the centre thereof from the upper fiat inflexible abrading surface 13 to the lower fiat, inflexible, abrading surface 14. The inner peripheral wall 15 of hone H forming opening 12 is preferably perpendicular to surfaces 13 and 14 and the diameter of the opening is preferably about one inch as compared to the preferred diameter of the hone of about three and one half inches.

One of the disadvantages of the usual elongated, rectan'gula'r block hone now in use is the fact that it tends to drag and adhere to the knife while the knife is being honed. As explained in my copending application Serial No. 240,823, filed August 8, 1951, now abandoned, I have discovered that forming a central opening in a hone thus making it of annular shape helps to prevent the formation of vacuums between the abrasive and work surfaces. Such an annular hone is especially useful in my new process wherein the hone lies fiat Within the concave face of the knife rather than bridging the concavity as in former honing processes.

About one inch of "the depth of hone H, from the diametrical, coarse abrasive surface 14 to the diametrical plane surface 16 is formed of coarse, sharp edged mineral crystals preferably a composition of 320 size grit silicon carbide abrasive combined with suitable bonding material, including naphthalene flakes, walnut shell powder, or the like to make the resulting annular element when fired, of a porous nature. The voids or pores in this annular element 17, of my hone are about of an inch in diameter and constitute in total about one fifth of the rigid mass of the annular element 17.

About one half inch of the hone H from the diametrical fine abrasive surface 13 to the diametrical plane surface 16 is formed of fine sharp edged mineral crystals preferably a composition of 600 size grit silicon carbide abrasive combined with suitable bonding material including Napthalene flakes, walnut shell powder, or the like to make the resulting annular element 18 when fired one of a porous nature. The voids, or pores in this second annular element 18 of my hone are about & of an inch in diameter and constitute in total about one fourth of the mass of section 18.

The first annular element 17 and the second annular element 18 are adhered together at their meeting surfaces on diametrical plane surface 16 by heat bonding of the abrasives when fired and no lamination material is in- 'serted at. 16 to prevent passage of liquid through hone H from surface 13 to surface 14.

In place of the usual honing fluids now in use, I provide a lubricating and wetting agent 30 made up of about mineral spirits, about 3% wetting agent and odor additive and about 12% spindle oil.; My new honing liquid aids the rapid abrasive action of my hone without allowing the hone to float on the liquid or to form a suction which retards the movement of the stone over the working surfaces. As shown in Fig. 10, I provide a pan 40,

having walls 41, a removable cover 42 and a screen floor 43 resting on the bottom 44 into which a small amount of my honing fluid is poured prior to the honing operation. The hone may be periodically placed on floor 43 and any abrasive grit picked up by the stone during honing falls through screen 43 onto bottom 44 or pan 40, and the cover 42 keeps dust or other foreign substances out of the pan and away from the hone or honing liquid.

The porous nature of my new hone, causes the honing liquid to be drawn upwardly from whichever surface 13 or 14 is immersed in the fluid 30, by capillary attraction, to the opposite upper surface. A single immersion of one diametrical surface of hone H, in fluid 30, contained in pan 40, thus rapidly saturates sections 17 and 18 throughout and forms a liquid coating on each abrasive surface 13 and 14 as shown in Fig. 10.

I provide a continuous band 19, preferably of metal, in the finger groove 11, of hone H, to prevent contact of the finger tips of the operator with the abrasive material of the hone. Band 19 also serves to give a firm grip for the fingers of the operator since it shields the fingers from honing liquid permeating through the abrasive material of the finger groove 11.

As shown in Figs. 4-8 the machine knife for which my hone is especially adapted is usually of high speed grade steel and is extremely dense and wear-resistant thus requiring considerable time to properly sharpen the edge by former methods. Knife K has a flat face 50, a narrow beveled cutting face 51, a cutting edge 52, a wider cutting face 53 and a bottom face 56. The narrow cutting face 51 is beveled at a predetermined angle to the wider cutting face 53 and it is desirable that this angle be constantly maintained so that the bevel does not become either shorter or longer. Cutting face 51 is concave to the extent of up to about two one thousandths of an inch at its low point 54 and cutting face 53 is concave in a considerably greater amount with its low point at 55, such as about four one thousandths of an inch.

After hone H has been thoroughly permeated by my honing liquid, as indicated in Fig. 10, a knife such as K is placed in the knife holding slot 70 of a block V. The narrow concave cutting face 51 is thus horizontal and the knife supported throughout its length by similar blocks suitably spaced. The rigid flat inflexible surface 14, of hone H, made up of the coarse abrasive of annular element 17 is applied by the hand of the operator in a straight band made up of progressively overlapping, substantially identical ellipses, from end to end of the narrow concave cutting face 51. Liquid 30 forms a thin lubricating and wetting coat between surface 14 and face 51 which is continually renewed by exposing of a new abrasive surface and by seepage and suction is avoided by the opening 12 together with the porous nature of the hone H.

Since surface 51 is slightly concave as at 54, the hone rides on the opposite upper portions of the concavity at 81 and 82 and flattens the same in a very small amount while retaining the exact angle of the bevel. One passage along the length of the knife is usually sufi'icient to sharpen the edge 52 and turn the feather edge over towards face 53 although one or more passages may be .added if necessary or desirable.

cutting edge 52 to remove the feather, or any sawtooth effect, in the edge. This blunted the cutting edge and usually necessitated repeating the step of honing the beveled face 51 with coarse abrasive to again secure a sharp cutting edge at 52. By my new process, I have been able to eliminate the step of honing the cutting edge 52 entirely and thus complete the honing operation in a shorter time and without repeated honing of the same surface.

It was formerly customary to place an elongated rectangular block of abrasive material on the wide cutting face 53 so that it projected over the cutting edge 52 and projected over the bottom face 56 thus bridging the concavity at 55. Honing in this manner, flattened the upper portions of the concavity at 57 and 58 and at 57, adjacent cutting edge 52, produced what is known as a double bevel. The angle of the bevel was thus changed slightly and caused the knife to cut inaccurately.

The next step of my process, therefore, consists in the application of hone H, by the hand of the operator, with its rigid, flat, inflexible surface 13, made up of the fine abrasive of annular element 18, in contact with that portion of concave surface 53 extending between low point 55 and cutting edge 52. The hone H is advanced in a straight band made up of progressively overlapping, substantially identical ellipses from end to end of knife K, but at no point passing beyond the line formed by low points 55. The concavity at 57, 55 and 58 is thus not changed, the original cutting edge of the knife is duplicated in the correct relation to the remainder of the knife K and the feather on cutting edge 52 is partially removed.

Knife K is then restored to slot of block V as shown in Figs. 7 and 8 and the rigid, flat, inflexible surface 13, made up of the fine abrasive of annular element 18 is applied by the hand of the operator to the narrow concave cutting face 51. The hone is advanced progressively in an overlapping elliptical path from end to end of cutting face 51 to complete my honing process and to remove all traces of feather on cutting edge 52.

As shown in Fig. 9, knife K, after honing may be placed in slot 71 of block V for inspection and testing of the sharpened edge 52 with a single sheet of paper drawn edgewise along the cutting edge 52.

I claim:

1. The process of sharpening a machine knife having a narrow concave face and a wider concave face said faces meeting at a cutting edge which method comprises first positioning said knife with its narrow concave face substantially horizontal and coarse honing both opposite longitudinal edges of said narrow concave face with an overlapping elliptical motion from end to end thereof; then positioning said knife with its wider concave face substantially horizontal and fine honing only the cutting edge half of said wider concave face from end to end with an overlapping elliptical motion and then again positioning sai'd knife with its narrow concave face substantially horizontal and fine honing both opposite longitudinal edges of said narrow concave face with an overlapping elliptical motion from end to end thereof.

2. The process of sharpening an elongated machine knife, said knife having a narrow, concave face angularly disposed to a wider concave face to form an elongated cutting edge which process comprises the steps of progressively coarse abrading both opposite longitudinal edges of said narrow face, simultaneously and in the same flat plane, without abrading the concavity in said narrow face; then progressively fine abrading the wider concave face of said knife in a flat plane extending from said elongated cutting edge to the deepest longitudinal line of concavity in said wider face, without abrading the remainder of said concavity, and then progressively fine abrading both opposite longitudinal edges of said narrow face, simultaneously and in the same flat plane, without abrading the concavity in said narrow face, thereby retaining the angular relationship of said faces during such sharpening.

3. A process as specified in claim 2 plus the step of continually seeping a coating of a lubricating and wetting liquid to each successive area of a face of said knife being abraded during said steps, thereby eliminating halts during or between steps to secure a resupply of said liquid.'

4. A process as specified in claim 2 wherein said abrading advances along each face of said knife in a' continu- 5 6 bus longitudinally extending, straight band defined by pro- 1,018,579 Miller Feb. 27, 1912 gressively overlapping substantially identical ellipses. 1,059,566 Rodgers Apr. 22, 1913 5. A process as specified in claim 2 plus'the steps of 1,470,762 Reneau Oct. 16, 1923 coating ail ubricating and wetting liquid by'seepage onto 1,867,623 Gouldbourn et a1 July 19, 1932 each successive area of a face of said knife being abraded 5 1,980,872 Moul Nov. 13, 1934 while continually connecting the central portion of said 2,191,719 Kuhlman Feb. 27, 1940 area to the'- 'atmosphere thereby relieving vacuums in said 2,269,556 St. Clair Jan. 13, 1942 central portion caused by abrading with a liquid coating.

FOREIGN PATENTS References C d in the m9 Of i P t 10 140 913 Great Britain No 10 1919 UNITED STATES PATENTS 437,733 Great Britain Oct. 28, 1935 272,345 Stephens Feb. 13, 1883 OTHER REFERENCES 763,764 J h Ju e 28, 1904 Publication Grits and Grinds by Norton Co., vol.

G d Se t, 20, 1910 15 41, No. 12, pages 3 to 13, inclusive, December 1950. 

